NATS 1510 Lecture Notes - Lecture 9: G. M. B. Dobson, Bromine, Soot
25 Nov 2016
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Document Summary
The sol started to form soon after the great oxygenation event (2. 45 bya) when oxygen started to accumulate in the atmosphere due to photosynthesis. Ozone layer did not fully form until 400 mya when green plants evolved and molecular oxygen mixing ratios reached their present level 21% In sept, oct, and nov of the year 1979, such emissions have caused up to 70% destruction of the ozone layer in the antarctic. Lesser reductions have occurred over the arctic in march, april, and may of each year. Recent international cooperation has helped replace emission of most ozone- depleting gasses with less destructive ones, reducing ozone loss. Global warming, which warms the troposphere and cools stratosphere, has delayed the recovery of the ozone layer. About 90% of all ozone molecules in the atmosphere reside in the stratosphere (good ozone) and the remaining reside in the troposphere (bad ozone)
